engleski

Exceptionally pyramidalized olefins: A theoretical study of the cyclopropenyl fused tricycles tricyclo[3.2.1.0(2,4)]oct-2(4)-ene, tricyclo[3.2.1.0(2,4)]octa-2(4),6-diene, tricyclo[3.2.2.0(2,4)]non-2(4)-ene, and tricyclo[3.2.2.0(2,4)]nona-2(4),6-diene

RHF, MP2, and TCSCF ab initio theory and B3LYP, B3PW91, and SVWN density functional theory were used to study the series of cyclopropenyl-fused tricycles 9-12. In each of 9-12, the cyclopropenyl double bond is exceptionally pyramidalized (butterfly angle psi similar to 41-50 degrees) with both endo and exo bent isomers. In the norbornyl systems (9 and 10), the endo bent isomers are more stable than the exo bent isomers, whereas in the bicyclo[2.2.2]octadiene 12 the reverse is true with the exo bent isomer being the low energy form. The activation barriers for the endo/exo interconversions are calculated to be relatively low (Delta H-not equal similar to 6-13 kcal/mol).

ALDER CYCLO-ADDITIONS; DOUBLE-BOND GEOMETRY; ELECTRONIC CONTROL; SYN-SESQUINORBORNATRIENE; CORRELATION-ENERGY; AB-INITIO; STEREOSELECTIVITY; ALKENES; CONSEQUENCES; NORBORNENE

nije evidentirano